/*
 * The MIT License (MIT)
 *
 * Copyright (c) 2014-2016 Ilkka SeppÃ¤lÃ¤
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

package com.iluwatar.retry;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Random;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.function.Predicate;

/**
 * Decorates {@link BusinessOperation business operation} with "retry" capabilities.
 *
 * @author George Aristy (george.aristy@gmail.com)
 * @param <T> the remote op's return type
 */
public final class RetryExponentialBackoff<T> implements BusinessOperation<T> {
  private final BusinessOperation<T> op;
  private final int maxAttempts;
  private final long maxDelay;
  private final AtomicInteger attempts;
  private final Predicate<Exception> test;
  private final List<Exception> errors;

    /**
     * Ctor.
     *
     * @param op the {@link BusinessOperation} to retry
     * @param maxAttempts number of times to retry
     * @param ignoreTests tests to check whether the remote exception can be ignored. No exceptions
     *     will be ignored if no tests are given
     */
  @SafeVarargs
  public RetryExponentialBackoff(
            BusinessOperation<T> op,
            int maxAttempts,
            long maxDelay,
            Predicate<Exception>... ignoreTests
  ) {
    this.op = op;
    this.maxAttempts = maxAttempts;
    this.maxDelay = maxDelay;
    this.attempts = new AtomicInteger();
    this.test = Arrays.stream(ignoreTests).reduce(Predicate::or).orElse(e -> false);
    this.errors = new ArrayList<>();
  }

    /**
     * The errors encountered while retrying, in the encounter order.
     *
     * @return the errors encountered while retrying
     */
  public List<Exception> errors() {
    return Collections.unmodifiableList(this.errors);
  }

    /**
     * The number of retries performed.
     *
     * @return the number of retries performed
     */
  public int attempts() {
    return this.attempts.intValue();
  }

  @Override
  public T perform() throws BusinessException {
    do {
      try {
        return this.op.perform();
      } catch (BusinessException e) {
        this.errors.add(e);

        if (this.attempts.incrementAndGet() >= this.maxAttempts || !this.test.test(e)) {
          throw e;
        }

        try {
          Random rand = new Random();
          long testDelay = (long) Math.pow(2, this.attempts()) * 1000 + rand.nextInt(1000);
          long delay = testDelay < this.maxDelay ? testDelay : maxDelay;
          Thread.sleep(delay);
        } catch (InterruptedException f) {
          //ignore
        }
      }
    }
    while (true);
  }
}

